Grass weeds cause trememdous global economic losses by reducing crop yields and lowering crop values. In particular, blackgrass, barnyardgrass, green foxtail and wild oats cause extensive economic losses worldwide. In addition some herbicides have caused some crop damage due to inadvertant application of excessive herbicide. For example, because a spray nozzle does not distribute the herbicide evenly.
Therefore, there is an ongoing search in the art to create more effective and more selective herbicidal agents for the selective control of grass weeds growing in the presence of crops and ones which give a better margin of safety so that inadvertent uneven application will not cause so much crop damage, perhaps eliminating such damage altogether.
Substituted alkyl ethers of phenoxyphenols are described in Great Britain Patent No. 1,572,125. However, the compounds described in the above-said patent are distinct from the compounds of the present invention. In addition, the compounds of the above-said patent are not particularly suitable for the selective control of blackgrass growing in the presence of crops at low application rates.
U.S. Pat. No. 4,661,149 discloses substituted phenoxypropionaldehyde derivatives which are outside the scope of the present invention.
It is, therefore, an object of the present invention to provide 2-(heteroaryloxyphenoxy)alkylsulfonates which are highly effective herbicidal agents useful for the selective control of grass weed species in the presence of crops.
It is also an object of this invention to provide certain 2-(heteroaryloxyphenoxy)alkylsulfonate herbicides that exhibit at least a 4.times. margin of safety when applied to blackgrass, barnyardgrass and green foxtail growing in the presence of cereal crops such as wheat and barley and at least a 16.times. margin of safety when used for the control of blackgrass, barnyardgrass and green foxtail growing in the presence of broadleaf crops such as soybean.
It is another object of this invention to provide a method for selectively controlling grass weeds in the presence of cereal crops utilizing a 2-(heteroaryloxyphenoxy)alkylsulfonate compound.